Improvement in g-rate-bars for steam-generators



MARSHALL3D.Y WELLMAN, OF ALLEGHENY COUNTY` PENNSYLVANIA.

Letters Patent No. 101,795, dated April 12, 1870.

IMPROVEMENT N GRATE-BARS FOR STEAM-GENERATORS.

The Schedule referred to in these Letters Patent and making part of thesame.

To all whom it may concern Be it known that I, MARSHALL D. W ELLMAN, ofthe county of Allegheny and State of Pennsylvania, have invented a newand useful Improvement in Grate- Bars; and I do hereby declare thefollowing to be a full, clear and exact description thereof, referencebeing had to the accompanying drawing making a part.

of this specication, in which- Figure l is a perspective view of myimproved grate-har.

Figure 2 is a longitudinal vertical section along the line x x.

Figure 3 is a cross section along the line x'.

Like letters of reference indicate like parts in each.

The nature of my invention consists in the construction of a grate-bar,having a box or hollow face for the reception of ashes, and madeentirely of thin plate metal, so that, while possessing the desiredstrength and durability, it will, with a minimum of metal, have amaximum -amount of surface exposed to the action of the air, and therebyalways be kept at a comparatively low temperature.

In bars as heretofore constructed the face of the bar made much heavierthan the weight of the lire abso-f lutely requires, and presentcomparatively a small cooling surface. Consequently there is an unneces-`:sary waste of metal, and also of labor in handling them, especiallywhile cleaning out the grate, as well as a lack of the desireddurability.

To enable others skilled in the art to make and use my improvement, Iwill proceed to describe its construction and mode of operation.

'The upper face of the grate-bar (figs. 1 3) is made hollow or of a boxform, as shown, or, in other words, the flanges b at the sides and thecenter rib b', if such .be used, extend up a short distance. above thebearing plate a, which then constitutes the bottom of the box af. Allthese parts are cast quite thin, so as to have on the sides of the angesb, rib b', and lower face o f' bearing plate a, the maximum ofheat-radiating surn face combined with a minimum of .thickness of met-alin anyone part. Hence, by the current of air which, rising from theash-pit below, passes over the parts named, the grate-bar will be keptcomparatively oooh' and is not liable to be burned out.

This result is still more perfectly secured by the introduction into theupper face of the bar of the box c', made in one, two, or.more divisionsat pleasure.

This box soon becomes filled to the l upper edgesfof the anges b b withashes, which, being a poor coliductor of heat, give the bearing plate a,as 'well as the inner faces of such ianges, the best possible protectionagainst the action of the heat of the fire.

rIhe under side of thcbearing end d should also be cast with hollowchambers'c, surrounded at the sides and on top by thin plates in orderto secure the most perfect and complete radiation of heat.

The grate-bar described may be made narrow or broad at pleasure, it onlybeing necessary in broad bars to increase thc number of central ribs b',so as to secure the desired strength. In narrow bars this central ribmaybe dispensed with.

I am aware that grooved or tluted faced-grate-bars for the reception ofashes are not new, and hence I claim the box form for the face of thebar only1 in connection with the thin plate sides and bottom, where: byin making the bars less metal lis required, and, in proportion to theamount of metal used, a maximum of radiating surface given, the betterto prevent the bars from being injuriously aiected by the heat. l

What I claim as my invention, and desire to secure by Letters Patent,is- 'l 1. A grate-bar having thin plate bottom and sides or anges,inclosing a hollow or box face, so as, with a minimum amount of metal,to secure a maximum amount of heat radiating surface, constructedsubstantially as set forth.

2. Chambering out the lower face of the bearing ends of grate-bars,substantially as described.

In testimony whereof, I, the said M. D. VVELLMAN, have hereunto set myhand.

MARSHALL D. WELLMAN.

Witnesses s A. S. Nrononson, Tiros. B. Kn-RR.

